Spring contact for electric plug couplings



July 29, 1947.

G. WAGSTAFF SPRING CQNTACT FOR ELECTRIC PLUG COUPLINGS Filed June 18, 1945.

raven/02 Patented July 29, 1947 OFFICE SPRING CONTACT FOR ELECTRIC PLUG COUPLINGS George Wagstafl', Long Eaton, England Application June 18, 1943, Serial No. 491,411 In Great Britain July 3, 1942 2 Claims. (Cl. 173-328) This invention relates to spring contacts for electric plug couplings of the kind wherein the spring contact is formed from a single strip of spring metal which is bent to form a base having a pair of upstanding lugs with ends bent over inwardly or outwardly and a depending wiring or soldering tag, the contact being fitted into a recess in an insulator, the wiring tag extending therethrough while the lugs are adapted to receive the contact pin of the plug or other part to be connected between them and to maintain a gripping contact therewith. v

Usually such contacts depend for their gripping power on the fact that the recess is of such a size that when the contact is inserted between the lugs parts of the lugs are forced into contact with the sides of the recess which assists the spring gripping action.

In some cases particularly when the insulator is of ceramic material it is not always possible to make the recess exactly the right size that is to say to work to close tolerances and thus it may be too small and compress the spring contact to such an extent that the contact pin cannot be inserted between the lugs or on the other hand it may be too large so that when the contact pin is inserted the spring lugs do not obtain the support from the side walls of the recess. Thus if the recess is too large the contact pin may be held only lightly by the spring lugs and a loose and unsatisfactory coupling will result.

The present invention has for its object to provide a spring contact in which the above defects are obviated. According to the invention the spring lugs of a contact member of the kind above described are reinforced by separate and independent spring means so arranged that sufilcient pressure is exerted on a pin or the like inserted between the lugs even if the recess is on the large side. Such spring means may consist of a U or V shaped spring, the free ends of which are passed into the recesses formed by the turnedover parts of the spring lugs so that the lugs or parts of them are embraced by this additional or reinforcing spring which extends in a plane substantially at right angles to the planes of the lugs.

To enable the invention to be fully understood it will now be described with reference to the accompanying drawings, in which:

Fig, 1 is a plan view of part of a valve holder embodying the present invention,

Fig. 2 is a sectional side view on the lines 2-2 of Fig. 1;

' Fig. 3.

As shown in the accompanying drawings a moulded valve holder indicated by the reference I is provided with a series of recesses 2 (one only being shown) to receive contacts for the pins of the thermionic valve. The contacts consist of a base 3 having lugs 4, the walls of which converge inwardly towards the outer ends. The free end portions of the lugs are bent outwardly and downwardly to provide angularly bent walls 5, 6 definining a recess 1. A U-shaped spring 8 is provided for reinforcing the resiliency of the lugs 4, the spring being separate and independent of the lugs and being assembled by inserting the free ends of the spring into the recess I. The contact has the usual wiring tag 9.

The dimensions of the reinforcing spring 8 naturally depend on the size of the recess 2 but preferably the spring is of sucha size that when assembled with the contact and in position in the -recess 2 there is only slight play between the ends of the spring and the adjacent walls of the recess.

The recess may have an undercut part or a shoulder shaped to retain or support the reinforcing spring 8 in position and an opening I'll is provided in the recess through which the wiring tag 9 of the spring contact extends. After assembly the spring contact may be secured, for example, by twisting or bending the tag 9 or the tag may be notched to provide a securing tongue which can be bent up or an embossment may be provided on the tag.

The reinforcing spring 8 may be formed from a suitable piece of spring wire and while it is preferably assembled as a separate part with the spring contact it may be permanently attached thereto if desired. The recess 2 may be so shaped that in cross-section the part thereof which houses the lugs of the contact has rectangular sides which merge into a tapered part which accommodates the U-shaped end of the reinforcing spring 8, the clearance between the sides of the recess 2 and the ends of the spring and the sides of the lugs being slight. An undercut part may be provided in the tapered part of the recess for receiving the U-shaped end of the reinforcing spring if desired.

The invention is particularly but not exclusively adapted for use with radio valve holders as in some cases the valve pins or contacts are of the needle type consisting of relatively small diameter described comprising a support-engaging base,

outwardly converging wings extending from the opposite sides of said base and presenting a spring tensioned prong-receiving contact socket, the outer end portions of said wings being bent outwardly and inwardly to provide spring armreceiving loops exteriorly of said socket, said loops being substantially closed against the outer sides of said wings but, open at least at one edge thereof, and a U-shaped spring having its end portions extending into the open end of said loops and bearing against the outer faces of said wings.

2. An electrical contact of the class described comprising a support-engaging base of substantially flat strip sheet metal provided with an angularly extending wiring tag at one end thereof, outwardly converging wings extending from opposite sides of asid base from the opposite end thereof and in a direction generally normal thereto and presenting a spring tensioned prong-receiving contact socket, the terminal end portions of said wings being looped outwardly over the outer sides of said 'wings and being substantially closed against a face thereof and presenting opposed pockets exteriorly of said wings open along at least one edge thereof, and a U-shaped spring having its end portions extending into the open end of said loops and bearing against the outer faces of said wings.

GEORGE WAGSTAFF.

REFERENCES CITED The following references are of record in the Number Name Date 1,719,288 Danielson July 2, 1929 1,990,087 Nichols et al Feb. 5, 1935 1,969,991 Robinson Aug. 14, 1934 2,320,623 Lopp et a1 June 1, 1943 FOREIGN PATENTS Number Country Date 506,546 Great Britain May 31, 1939 812,905 France May 20, 1937 749,388 France July 22, 1933 682,399 Germany Oct. 19, 1939 

